HVDC power transmission has become increasingly important due to increasing need for power supply or delivery and interconnected power transmission and distribution systems. In a HVDC power system there is generally included an interface arrangement including or constituting a HVDC converter station, which is a type of station configured to convert high voltage DC to AC, or vice versa. A HVDC converter station may comprise a plurality of elements such as the converter itself (or a plurality of converters connected in series or in parallel), one or more transformers, capacitors, filters, and/or other auxiliary elements. Converters may comprise a plurality of solid-state based devices such as semiconductor devices and may be categorized as line-commutated converters (LCCs) or voltage source converters (VSCs), e.g. depending on the type of switches (or switching devices) which are employed in the converter. A plurality of solid-state semiconductor devices such as IGBTs may be connected together, for instance in series, to form a building block, or cell, of a HVDC converter.
HVDC Light is a technology developed by ABB and that is based on VSC technology and is designed to transmit power for example underground and underwater, and also over relatively long distances. HVDC Light based power systems may be capable of black start operation, i.e. they may have a capability of starting transferring power from an operating power system or grid to another power system or grid that suffered a blackout, or to an ‘islanded’ or isolated power system. A HVDC converter station is often equipped with auxiliary systems or elements such as systems which may provide or facilitate cooling, water purification, communications and/or control of operation of the HVDC converter station. It is often desired or even required that some or even all of such auxiliary systems should be operational before the actual black start of the HVDC link is performed. Prior to the black start of the HVDC link power is usually provided to such auxiliary systems by means of a diesel generator or the like. However, in some applications it may be disadvantageous or difficult or not feasible (or even impossible) to use diesel generators or the like. For example in case a HVDC converter station is located offshore, the use of diesel generators to provide its auxiliary systems with power prior to black start operation may be associated with relatively high costs relating to maintenance of the diesel generators. Use of diesel generators may also have a negative environmental impact due to need for storing fuel, etc. Also in a case where the HVDC converter station is located offshore, a dedicated AC transmission line for supplying auxiliary power to any auxiliary systems of the HVDC converter station may not be feasible for distances of more than a few hundred kilometers between the HVDC converter station to the shore due to relatively high reactive power consumption by the long capacitive cable that may be required for the AC transmission.
US 2014/0268926 A1 discloses a black start configuration that may be used with a HVDC transmission system including a HVDC conduit, which black start configuration comprises buck converters. According to US 2014/0268926 A1 a black start flow path can be formed, bypassing a transformer at the inverter side, HVDC inverter devices, HVDC rectifier devices and a transformer at the rectifier side, and directly coupling the buck converters with the HVDC conduit. However, there is still need in the art for an improved power transmission arrangement means for facilitating or enabling carrying out a black start of a HVDC link.